Android: Add driver "all" option to enable all drivers

Add a driver string "all" so that if BOARD_GPU_DRIVERS is set to "all",
all the drivers are enabled in the build. This makes build testing all
drivers easier to maintain.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/Android.mk b/Android.mk
index 71140df..e2d792d8 100644
--- a/Android.mk
+++ b/Android.mk
@@ -55,6 +55,10 @@
 	vc4.HAVE_GALLIUM_VC4 \
 	virgl.HAVE_GALLIUM_VIRGL
 
+ifeq ($(BOARD_GPU_DRIVERS),all)
+MESA_BUILD_CLASSIC := $(filter HAVE_%, $(subst ., , $(classic_drivers)))
+MESA_BUILD_GALLIUM := $(filter HAVE_%, $(subst ., , $(gallium_drivers)))
+else
 # Warn if we have any invalid driver names
 $(foreach d, $(BOARD_GPU_DRIVERS), \
 	$(if $(findstring $(d).,$(classic_drivers) $(gallium_drivers)), \
@@ -64,6 +68,7 @@
 )
 MESA_BUILD_CLASSIC := $(strip $(foreach d, $(BOARD_GPU_DRIVERS), $(patsubst $(d).%,%, $(filter $(d).%, $(classic_drivers)))))
 MESA_BUILD_GALLIUM := $(strip $(foreach d, $(BOARD_GPU_DRIVERS), $(patsubst $(d).%,%, $(filter $(d).%, $(gallium_drivers)))))
+endif
 $(foreach d, $(MESA_BUILD_CLASSIC) $(MESA_BUILD_GALLIUM), $(eval $(d) := true))
 
 # host and target must be the same arch to generate matypes.h